A barcode is an optical machine-readable representation of data. Originally, barcodes represented data by varying the widths and spacings of parallel lines. These types of barcodes may be referred to as linear or one-dimensional (1D) barcodes. Later, barcodes evolved into rectangles, dots, hexagons and other geometric patterns in two dimensions (2D). Although 2D systems use a variety of symbols, they are generally referred to as barcodes as well. Devices for identifying or extracting information from barcodes are generally referred to as barcode readers.
Barcodes and barcode readers have a wide variety of uses. For example, almost every item from a grocery store, department store, or a mass merchandiser has a barcode on it. In addition, barcodes are widely used in the healthcare and hospital settings for patient identification, medication management, etc. Barcodes are used to keep track of rental cars, airline luggage, registered mail, express mail and parcels, etc. Barcoded tickets allow the holder to enter sports arenas, cinemas, theatres, fairgrounds, etc.